Kill switch how-to

[MetroMPG]

I have to say you have my interest with the name of your car though - "aerometro". Post an intro thread!

[RealGomer]

Is this a possibility? If you could figure out what sensors under what conditions trigger the Deceleration Fuel Cut Off (DFCO) it might be worthwhile to figure out how to trick the computer to do all the work. Each car may be a bit different; but if the appropriate sensor feed voltages could be adjusted by the push of one button; it should activate the DFCO and not set off any fault codes. This should ensure that all emmisions systems would activate properly, i.e. no fuel dumping outside of engine spec.

[bbjsw10]

Originally Posted by RealGomer

Is this a possibility? If you could figure out what sensors under what conditions trigger the Deceleration Fuel Cut Off (DFCO) it might be worthwhile to figure out how to trick the computer to do all the work. Each car may be a bit different; but if the appropriate sensor feed voltages could be adjusted by the push of one button; it should activate the DFCO and not set off any fault codes. This should ensure that all emmisions systems would activate properly, i.e. no fuel dumping outside of engine spec.

I would assume this is from tach pickup showing above certain rpm and tps showing idle position, you could some how use a 555 to make a high false tach signal and tps is already at idle position when EOC-ing. My thoughts anyway I do like the idea though. I would think a latching circuit would be nice for this one push to engage then push again to disengage.

[RealGomer]

I drive an automatic and I noticed today that DFCO doesn't kick in unless I am going 45+ mph. Thinking about that, on an automatic, the torque converter has to be locked or the engine will die. Keep the safety in mind with any mods - would hate to loose power steering/brakes at "just the wrong time".

[bbjsw10]

Originally Posted by RealGomer

Keep the safety in mind with any mods - would hate to loose power steering/brakes at "just the wrong time".

This is the main reason I stuck with K.I.S.S. method of the switch. I have full control over when and where it occurs. I do like the idea of tricking ecu into a DFCO mode though. I may try this when weather warms. Too cold for EOC right now. Don't want to kill my battery.

[Xringer]

Originally Posted by bbjsw10

I would assume this is from tach pickup showing above certain rpm and tps showing idle position, you could some how use a 555 to make a high false tach signal and tps is already at idle position when EOC-ing. My thoughts anyway I do like the idea though. I would think a latching circuit would be nice for this one push to engage then push again to disengage.

I like your idea. A DPDT relay could be used to inject the false signals..


It's funny that you mentioned the 555. I was thinking about using the
555 method for tricking the Cruise Control into maintaining a fixed Throttle setting..

The trick would involve using a toggle switch to disconnect the tach signal
from the ECU and feed the 555 output into the ECU..
(Simulating around 2500 RPM).
Then, when the CC was engaged, it would hold the Throttle in place
and never move it, because the 555 is making it look like the RPMs
are staying the same..

If that actually worked, it might be useful in preventing the CC from
instantly applying power for every little hill on the road..

-----

If I turned the RPM tricker on when going slow down a steep hill, took my foot off the gas (TPS=10),
What would be the fake RPM range to put me into fuel-cut-off mode?

The reason I would want to do this: To allow me to shift into 'N' and not have
any Engine braking.. And, be able to enter Fuel-cut-off..
Without engine braking, I could get longer & faster coasts..
Plus, I'm still thinking of using a small ICE-Assist motor (Weak-Hybrid)
and no ICE braking would allow for nicer Re-Gen..

[Funny]

Originally Posted by Xringer

The reason I would want to do this: To allow me to shift into 'N' and not have
any Engine braking.. And, be able to enter Fuel-cut-off..
Without engine braking, I could get longer & faster coasts..
Plus, I'm still thinking of using a small ICE-Assist motor (Weak-Hybrid)
and no ICE braking would allow for nicer Re-Gen..

I like the idea you had for the Cruise Control, but what you are describing in this second section is the equivalent (though much more complicated) to installing a kill switch. If your car goes into Cut-off in neutral, it would shut off, it would not be able to keep turning without the assistance of the tranny to rotate it.

[Xringer]

Originally Posted by Funny

I like the idea you had for the Cruise Control, but what you are describing in this second section is the equivalent (though much more complicated) to installing a kill switch. If your car goes into Cut-off in neutral, it would shut off, it would not be able to keep turning without the assistance of the tranny to rotate it.

Oh yeah! Haha.. You are right! Near the bottom of the hill, I would have
to shift back into a gear and ease out the clutch to re-start it..

Oh well, I'll just stick to the basics. I still want some re-gen, but I guess
it's not going to be as much amperage..
I'm not sure a battery pack would want 30 second pluses of high amperage anyways.

I've been thinking of using a pot to pre-set the re-gen at only 100-300 watts
of re-charge. Have it come on with the brake lights and/or manual switch.

If I was on a long stretch of downhill road, getting about 40 MPG, I could
click on the re-gen, and adjust the pot so I was getting about 35 MPG,
IF I really wanted to charge up the pack for some reason.
Like if it was really low and I was not going back home to plug-in for a while..

[dcb]

FYI, did a saturn s-series kill switch by putting a Normally Closed microswitch on the shifter in series with the "purple" crankshaft sensor wire by the ECU connection.

It's perfect, no codes, ignition and fuel both shut off when it is held in (even when engine braking) so it doesn't stumble on at all, and doesn't seem to have any strange side effects like the FI fuse rig did.

So far I've had good results with:
metro: interrupt cam signal
saturn: interrupt crankshaft signal

Difference being the metro has a distributor.

Of course you can use relays to interrupt both fuel and ignition but that complicates things and you would have two or more "switches" that can fail instead of one.

[HilseeJ]

Did you solder the male spade connectors into the fuse box or just push them into place?